Conversations with my boss. RE: ttc

So I switched departments two months ago and with it my boss changed. I have had no issues and my company has a great flex opportunity when you need off early or need to come in late. You can "flex" up to 4 hours/month used in two seperate occassions with the time being made up in the same week. No bigge.

 Well now we get into the "fun" part of ttc with clomid. I have to go get day 21 bloodwork....well that falls on a friday this month and there is one lab location open at 6 am so I will make that work. Then I call the ob office. I literally make my next appointment the day af shows next month if i do not get pregnant. The nurse says they do it all of the time. I call cd1 and they squeeze me in that day or first thing the next day...say what?

I go to my boss and try to explain to him that I may have to use some "flex time" without the usual 24 hour notice because I may have a doctor's appointment that i cannot schedule until the day of. I was essentially trying to explain it without saying look the first day of my next period I have to go see my doctor if I do not get pregnant this month. I eventually skirted it by telling him I was undergoing some fertility treatments and they were time sensetive and unfortunately cannot be planned in advance. That caught understanding until he said "Well as long as this is not a monthly, recurring thing..." FAIL. I wanted to laugh or cry or both really (darn hormones) but instead I calmly replied, "Everyone involved hopes things get resolved quickly but feritlity issues tend to have a mind of their own." and smiled sweetly. Which I believe finally clicked because he told me to put it in writing...